Lateral chromatic aberration is a color artifact that degrades image sharpness and color quality. Lateral chromatic aberration is a phenomenon that occurs when a scene is imaged by an optical system. For example, a lens of an optical system refracts different wavelengths differently from one another. Under these circumstances, one color component of an object in the scene, is projected onto an electronic sensor at a different magnification than another color component of the object. The mismatch of magnification between the color components causes distortions such as fringes around the borders or boundaries of the depiction of the object in the image.
Inasmuch as chromatic aberration is caused by different wavelengths of light being projected at different magnifications, one proposal for the correction of the image degradation is to scale or adjust the image formed by each wavelength by a respective corrective magnification. For example, in digital photography, the wavelengths are grouped into three color channels, red, green and blue (RGB). Each of the separate color channels is spatially magnified by a correction factor until the aberrations are eliminated. In some commercially available digital editing applications a user is able to manually adjust channel magnifications until the resulting image is pleasing to the eye.
An automated method for calculating magnification correction factors utilizes a photograph of a known black and white grid. From the image projected from the grid, a comparison can be made to determine various shifts in the image resulting from channel magnifications. From the shift information, calculations of magnification factors can be executed and used to calibrate the optical system for correct image projection during future use. Some camera equipment, such as television camera implement an automatic chromatic aberration correction system that compares edge features in each of the color channels, and attempts to line up the edges using an error signal generated from the comparison.